STV only makes sense for multi-winner elections. It fundamentally does not pick the best candidate - just the first who can scrape together sufficient support. A person can be literally everyone's second choice and still lose.

Approval is a straight improvement over FPTP - there is no good reason, at all, to prefer FPTP. It completely eliminates the way similar candidates cannibalize each other's votes. It minimizes self-defeating efforts to be "strategic" by ranking no-chance buttheads higher, or only giving your preferred frontrunner half a vote.

If you're gonna do ranked ballots to pick one candidate then use a Condorcet method.

And this type of disagreement on what sort of system to move to is among the reasons the lukewarm effort Trudeau attempted fizzled out pretty much immediately.